1. Field of the Invention
This disclosure relates to a fuel injection control device and a fuel injection control method for an internal combustion engine.
2. Description of Related Art
An electromagnetic fuel injection valve that is disposed in an internal combustion engine such as an automotive internal combustion engine is configured to be provided with a valve body which is opened in response to energization of an electromagnetic solenoid and be capable of adjusting a fuel injection quantity by an energization time of the electromagnetic solenoid being changed. The valve body of the fuel injection valve is subjected to a bounce motion immediately after full opening due to a reaction to a collision at a time of arrival at the fully open position. This bounce motion results in a variation of the injection quantity of the fuel injection valve. An effect that this bounce motion has on injection quantity accuracy during full lift injection in which the valve body is at the full opening becomes relatively significant as the injection quantity decreases. An internal combustion engine disclosed in Japanese Patent Application Publication No. 2014-025419, a lower limit (minimum energization time) is provided for the energization time of the fuel injection valve so that the injection quantity variation attributable to the bounce motion is kept at or below an allowable value.
When it comes to an internal combustion engine in which a fuel pumped from a fuel tank by a feed pump is pressurized by a high-pressure fuel pump and supplied to the fuel injection valve, examples of which include an internal combustion engine performing in-cylinder injection, a fuel pressure control is performed so that the fuel supplied to the fuel injection valve has a pressure (actual fuel pressure) controlled to correspond to a target fuel pressure set in accordance with an engine load or the like. During the fuel pressure control, the amount of the fuel discharged from the high-pressure fuel pump is adjusted for the actual fuel pressure to approach the target fuel pressure. At a time of a low load when a required injection quantity per injection is small, the target fuel pressure for the fuel pressure control might be set to a pressure lower than that at a time of a high load such that the energization time required for the injection of the fuel equivalent to a required amount (required energization time) does not fall short of a minimum energization time.